Fixes: 1) Corrected `ForeignKey` type assertions across models; 2) Resolved typos and formatting inconsistencies in `.env` and README; 3) Fixed explicit boolean checks in user manager methods.
Extra: Updated type hints in multiple models, serializers, and views.
Updated email sending logic across multiple modules to utilize `django.core.mail.get_connection` for better email connection management and efficiency. Adjusted filters in `conditions.py` to correctly handle dictionary inputs when checking attribute lengths.
